Methods and compositions for sealing pipe and forming barriers in well bores

ABSTRACT

The present invention provides methods and compositions for sealing pipes or forming barriers in well bores. A hardenable, low density sealing composition of the invention basically comprises a hardenable furan liquid resin mixture, an organosilane coupling agent, a cationic surfactant and hollow microspheres.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to methods andcompositions for forming barriers in well bores such as barriers in theannulus between a casing, liner or screen and the walls of a well bore.

[0003] 2. Description of the Prior Art

[0004] In the completion of well bores penetrating subterraneanproducing zones, casings or liners are often sealed therein to preventthe inflow or outflow of fluids. The sealing composition utilized hasgenerally been a cement composition having a relatively high density.The high density requires the use of special cement composition pumpingequipment which is costly to obtain and use to pump the cementcomposition into the annulus between the casing or liner and the wallsof the well bore. Also, the high density of the cement compositionincreases the well head pressure during pumping which can and often doesform undesirable fractures in the walls of the well bore.

[0005] A well completion operation often conducted in the portion of awell bore penetrating a subterranean producing zone is gravel packing.In gravel packing operations, particles referred to in the art as gravelare carried to the subterranean producing zone in which a gravel pack isto be placed by hydrocarbon or water carrying fluids. Prior to placingthe gravel particles in the subterranean zone, a screen is often placedin the subterranean zone for retaining the gravel particles in the zone.After the screen is placed in the zone, the gravel particles are pumpedinto the zone between the walls of the well bore and the screen therein.Once the particles are placed in the zone, the treating fluid leaks offinto the zone and/or it is returned to the surface. The gravel packproduced functions as a filter to separate formation solids fromproduced fluids while permitting the produced fluids to flow into andthrough the well bore.

[0006] After a subterranean producing zone has been gravel packed andproduced, it is often necessary to isolate one or more portions of theproducing zone to prevent the inflow of undesirable fluids such as saltwater using a hardenable, low density sealing composition. Whilehardenable low density sealing compositions have been developed and usedheretofore, there are continuing needs for improved hardenable, lowdensity sealing compositions for sealing pipe or forming annularbarriers in well bores. In addition, there are needs for such sealingcompositions that can be placed into a gravel pack by directly injectingthe hardenable, low density sealing compositions through gravel packscreens or expandable screens.

SUMMARY OF THE INVENTION

[0007] By the present invention improved methods and compositions forsealing pipe and forming barriers in well bores are provided which meetthe needs described above and overcome the shortcomings of the priorart. The hardenable, low density sealing compositions of this inventionare furan sealant compositions which are very resistant to chemicals andhigh temperature environments. The furan sealing compositions alsoprovide greatly superior and longer lasting seals between well bores andstrings of pipe as well as for forming barriers in well bores than thesealing compositions used heretofore.

[0008] The sealing compositions of this invention are basicallycomprised of a hardenable furan liquid resin mixture, an organosilanecoupling agent, a cationic surfactant, and hollow microspheres. Thesealing compositions can also optionally include a solvent or diluent, adispersing agent, and a light weight filler.

[0009] The methods of this invention for sealing pipe or forming abarrier in a well bore are comprised of the following steps. Ahardenable, low density sealing composition is prepared comprising ahardenable furan liquid resin mixture, an organosilane coupling agent, acationic surfactant, and hollow microspheres. The sealing composition isplaced in a well bore and then allowed to harden into an impermeablemass.

[0010] The objects, features and advantages of the present inventionwill be readily apparent to those skilled in the art upon a reading ofthe description of preferred embodiments which follows.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0011] The hardenable, low density sealing compositions of thisinvention basically comprise a hardenable furan liquid resin mixture, anorganosilane coupling agent, a cationic surfactant, and hollowmicrospheres.

[0012] Furan resin can withstand high temperatures withoutdeterioration, i.e., temperatures up to about 600° F., and are resistantto contact with harsh chemicals. Furan resin is self-catalyzed and curesat temperatures above about 275° F. At temperatures below about 275° F.,a delayed or encapsulated catalyst is utilized to cause the furan resinto cure and harden.

[0013] The hardenable furan liquid resin mixture in the sealingcomposition of this invention comprises a 2-furanmethanol homopolymerpresent in the mixture in an amount in the range of from about 55% toabout 60% by weight thereof and furfuryl alcohol present in the mixturein an amount in the range of from about 40% to about 45% by weightthereof. The furan liquid resin mixture is present in the sealingcomposition in an amount in the range of from about 10% to about 50% byweight thereof, preferably in an amount of about 35%.

[0014] Various solvents or diluents can optionally be used to thin downthe resin mixture if necessary to obtain a desirable viscosity andespecially when solid particulate fillers are blended in the resinmixture. Examples of solvents or diluents that can be used include, butare not limited to, 2-butoxy ethanol, butyl acetate, furfuryl acetate,or mixtures thereof. Of these, furfuryl acetate is preferred. When used,the solvent or diluent is included in the sealing composition in anamount in the range of from about 5% to about 60% by weight of thesealing composition.

[0015] Examples of organosilane coupling agents that can be utilized inthe sealing compositions include, but are not limited to,N-2-(aminoethyl)-3-aminopropyltrimethoxysilane,3-gylcidoxypropyltrimethoxysilane andn-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane. Of these,n-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane is preferred. Theorganosilane coupling agent is included in the sealing composition in anamount in the range of from about 0.1% to about 3% by weight thereof,preferably in an amount of about 1%.

[0016] The cationic surfactant in the sealing composition functions toimprove the contact of the furan sealing composition with surfaces ofparticulate fillers and strengthen the bond of the sealing compositionto the surfaces it contacts. Examples of cationic surfactants that canbe used include, but are not limited to, ethoxylated nonyl phenolphosphate ester, C₁₂-C₂₂ alkyl phosphonates, and mixtures of one or morecationic surfactants and one or more non-ionic surfactants. Of these, aC₁₂-C₂₂ alkyl phosphonate surfactant is preferred. The cationicsurfactant is present in the sealing composition in an amount in therange of from about 0.1% to about 10% by weight thereof, preferably inan amount of about 5%.

[0017] Examples of dispersing agents that can optionally be utilized inthe sealing compositions include, but are not limited to,naphthalene-sulfonate-formaldehyde condensates,acetone-formaldehyde-sulfite condensates and glucano-delta-lactone. Ofthese, naphthalene-sulfonate-formaldehyde condensates are preferred.When used, the dispersing agent which functions to disperse solids inthe sealing composition is generally present in the sealing compositionin an amount in the range of from about 0.1% to about 5% by weightthereof, preferably in an amount of about 1%.

[0018] A variety of light weight fillers can optionally be included inthe sealing composition including, but not limited to, amorphous silica,fumed silica, diatomaceous earth and fly ash. Of these, amorphous silicais preferred. When used, the light weight filler is present in thesealing composition in an amount in the range of from about 5% to about50% by weight thereof, preferably in an amount of about 30%.

[0019] The hollow microspheres are included in the sealing compositionsof this invention to lower the density of the compositions. A variety ofhollow microspheres can be utilized in accordance with this inventionincluding, but not limited to, hollow mineral glass spheres that arecommercially available under the trade name “SPHERELITES™” fromHalliburton Energy Services of Duncan, Okla.; hollow cenospheres formedof silica and alumina filled with low pressure gases commerciallyavailable under the trade designation “CENOLIGHT®” from Microspheres,S.A.; hollow microspheres that are formed of glass and are commerciallyavailable under the trade designation “SCOTCHLIGHT™” from the 3-MCompany of St. Paul, Minn.; and microspheres formed of ceramic materialthat are commercially available under the trade designation “Z-LIGHTSPHERES™” from the 3-M Company of St. Paul, Minn. Of these, mineralglass spheres are generally preferred. The hollow microspheres utilizedare generally present in the sealing composition in an amount in therange of from about 5% to about 50% by weight thereof.

[0020] The sealing compositions of this invention can also optionallyinclude sand as an additional filler. When used, the sand preferably hasa mesh size in the range of from about 70 mesh to about 140 mesh and ispresent in the sealing composition in an amount in the range of fromabout 5% to about 30% by weight of the sealing composition.

[0021] As mentioned above, when the temperature to which a sealingcomposition of this invention is exposed is below about 275° F., thesealing composition includes a delayed catalyst for causing the sealingcomposition to harden. While a variety of catalysts can be utilized,presently preferred catalysts include, but are not limited to,encapsulated hydrochloric acid, encapsulated maleic acid, encapsulatedsalicylic acid, encapsulated sodium bisulfate, encapsulated phosphoricacid, and encapsulated sulfonic acid. Of these, encapsulated sulfonicacid is the most preferred. The encapsulated material on the catalystsslowly dissolves or otherwise releases the catalysts over time. Whenused, the catalyst is present in the sealing composition in an amount inthe range of from about 0.1% to about 5% by weight of the composition.

[0022] The low density furan sealing compositions of this inventioninclude solid materials of small diameters whereby the compositions canbe injected through sand screens and the like to form annular barrierstherein. Additionally, the low density furan sealing compositions can beutilized for sealing casing and liners in well bores, for sealing holesand cracks in casing and liners, for sealing voids in the annulusesbehind sand control screens or expandable screens, and for pluggingfractures and the like in well bores.

[0023] The methods of the present invention for sealing pipe or forminga barrier in a well bore basically comprise the following steps. Ahardenable, low density sealing composition is prepared or providedcomprising a hardenable furan liquid resin mixture, an organosilanecoupling agent, a cationic surfactant, and hollow microspheres. Thesealing composition is placed in the well bore and then allowed toharden into an impermeable mass therein.

[0024] A preferred hardenable, low density sealing composition of thisinvention comprises: a hardenable furan liquid resin mixture; anorganosilane coupling agent; a cationic surfactant; and hollowmicrospheres.

[0025] A preferred method of sealing pipe or forming a barrier in a wellbore comprises the steps of: (a) preparing or providing a hardenable,low density sealing composition comprising a hardenable furan liquidresin mixture, an organosilane coupling agent, a cationic surfactant,and hollow microspheres; (b) placing the sealing composition in the wellbore; and (c) allowing the sealing composition to harden into animpermeable mass.

[0026] In order to further illustrate the methods and compositions ofthis invention, the following example is given.

EXAMPLE

[0027] A number of samples of the low density sealant compositions ofthe present invention were prepared containing furan liquid resinmixtures comprising 55% of 2-furanmethanol by weight and 45% furfurylalcohol by weight purchased from Durez Corp. of New York. The furanliquid resin mixtures were mixed with butyl acetate diluent or furfurylacetate diluent and the resulting mixtures were then blended withN-2-(aminoethyl)-3-aminopropyltrimethoxysilane, sodium bisulfate acidcatalyst, water for dissolving the acid catalyst, 70/170-mesh sandfiller, and hollow microspheres. The samples were then cured at atemperature of 325° F. for various cure times. After curing, thecompressive strengths of the samples were measured. The amounts of thecomponents in each low density sealant composition sample, the curingtimes of the samples, and the compressive strengths of the samples aregiven in Table 1 below. TABLE 1 Composition Sample 1 Sample 2 Sample 3Sample 4 Furan System, mL 20 20 20 20 Butyl Acetate (BA) or 5 (BA) 5(BA) 5 (FA) 5 (FA) Furfuryl Acetate (FA), mL Silane coupling agent, 0.20.2 0.2 0.2 mL Sodium Bisulfate, grams 1 3 1 3 Water, mL 1 3 1 370/170-mesh sand, grams 1 3 1 3 Hollow Microspheres 1 3 1 3 (Z-LIGHTSPHERES ™), grams Cure time @ 325° F., 96 96 96 96 hours CompressiveStrength, 3609 3504 5915 6218 psi

[0028] Thus, the present invention is well adapted to carry out theobjects and attain the ends and advantages mentioned as well as thosewhich are inherent therein. While numerous changes may be made by thoseskilled in the art, such changes are encompassed within the spirit ofthis invention as defined by the appended claims.

What is claimed is:
 1. A method of sealing pipe or forming a barrier ina well bore comprising the steps of: (a) preparing or providing ahardenable, low density sealing composition comprising a hardenablefuran liquid resin mixture, an organosilane coupling agent, a cationicsurfactant, and hollow microspheres; (b) placing said sealingcomposition in said well bore; and (c) allowing said sealing compositionto harden into an impermeable mass.
 2. The method of claim 1 whereinsaid hardenable furan liquid resin mixture comprises a 2-furanmethanolhomopolymer present in said mixture in an amount in the range of fromabout 55% to about 60% by weight thereof and furfuryl alcohol present insaid mixture in an amount in the range of from about 40% to about 45% byweight thereof.
 3. The method of claim 1 wherein said hardenable furanliquid resin mixture is present in said sealing composition in an amountin the range of from about 10% to about 50% by weight thereof.
 4. Themethod of claim 1 wherein said organosilane coupling agent is selectedfrom the group consisting ofN-2-(aminoethyl)-3-aminopropyltrimethoxysilane,3-gylcidoxypropyltrimethoxysilane andn-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane.
 5. The method ofclaim 1 wherein said organosilane coupling agent isN-2-(aminoethyl)-3-aminopropyltrimethoxysilane.
 6. The method of claim 1wherein said organosilane coupling agent is present in said sealingcomposition in an amount in the range of from about 0.1% to about 3% byweight thereof.
 7. The method of claim 1 wherein said cationicsurfactant is selected from the group consisting of ethoxylated nonylphenol phosphate ester, C₁₂-C₂₂ alkyl phosphonates and mixtures of oneor more cationic surfactants and one or more non-ionic surfactants. 8.The method of claim 1 wherein said cationic surfactant is a C₁₂-C₂₂alkyl phosphonate.
 9. The method of claim 1 wherein said cationicsurfactant is present in said sealing composition in an amount in therange of from about 0.1% to about 10% by weight thereof.
 10. The methodof claim 1 wherein said hollow microspheres are selected from the groupconsisting of hollow mineral glass spheres, hollow silica-aluminaspheres, glass spheres and ceramic spheres.
 11. The method of claim 1wherein said hollow microspheres are mineral glass spheres.
 12. Themethod of claim 1 wherein said hollow microspheres are present in saidsealing composition in an amount in the range of from about 5% to about50% by weight thereof.
 13. The method of claim 1 wherein said sealingcomposition further comprises a solvent or diluent selected from thegroup consisting of 2-butoxy ethanol, butyl acetate, furfuryl acetateand mixtures thereof.
 14. The method of claim 13 wherein said sealingcomposition is furfuryl acetate.
 15. The method of claim 13 wherein saidsolvent or diluent is present in said sealing composition in an amountin the range of from about 5% to about 60% by weight thereof.
 16. Themethod of claim 1 wherein said sealing composition further comprises adispersing agent selected from the group consisting ofnaphthalene-sulfonate-formaldehyde condensate,acetone-formaldehyde-sulfite condensate and glucano-delta-lactone. 17.The method of claim 16 wherein said dispersing agent isnaphthalene-sulfonate-formaldehyde condensate.
 18. The method of claim16 wherein said dispersing agent is present in said sealing compositionin an amount in the range of from about 0.1% to about 10% by weightthereof.
 19. The method of claim 1 wherein said sealing compositionfurther comprises a lightweight, filler selected from the groupconsisting of amorphous silica, fumed silica, diatomaceous earth, andfly ash.
 20. The method of claim 19 wherein said lightweight filler isamorphous silica.
 21. The method of claim 19 wherein said lightweightfiller is present in said sealing composition in an amount in the rangeof from about 5% to about 50% by weight thereof.
 22. The method of claim1 wherein said sealing composition further comprises sand.
 23. Themethod of claim 22 wherein said sand has a mesh size in the range offrom about 70 mesh to about 140 mesh.
 24. The method of claim 22 whereinsaid sand is present in said sealing composition in an amount in therange of from about 5% to about 30% by weight thereof.
 25. The method ofclaim 1 wherein said sealing composition further comprises a delayedcatalyst for causing said sealing composition to harden selected fromthe group consisting of encapsulated hydrochloric acid, encapsulatedmaleic acid, encapsulated salicylic acid and encapsulated sodiumbisulfate.
 26. The method of claim 25 wherein said delayed catalyst isencapsulated sodium bisulfate.
 27. The method of claim 25 wherein saiddelayed catalyst is present in said sealing composition in an amount inthe range of from about 0.1% to about 5% by weight thereof.
 28. Ahardenable, low density sealing composition comprising: a hardenablefuran liquid resin mixture; an organosilane coupling agent; a cationicsurfactant; and hollow microspheres.
 29. The sealing composition ofclaim 28 wherein said hardenable furan liquid resin mixture comprises a2-furanmethanol homopolymer present in said mixture in an amount in therange of from about 55% to about 60% by weight thereof and furfurylalcohol present in said mixture in an amount in the range of from about40% to about 45% by weight thereof.
 30. The sealing composition of claim28 wherein said hardenable furan liquid resin mixture is present in anamount in the range of from about 10% to about 50% by weight thereof.31. The sealing composition of claim 28 wherein said organosilanecoupling agent is selected from the group consisting ofN-2-(aminoethyl)-3-aminopropyltrimethoxysilane,3-gylcidoxypropyltrimethoxysilane andn-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane.
 32. The sealingcomposition of claim 28 wherein said organosilane coupling agent isN-2-(aminoethyl)-3-aminopropyltrimethoxysilane.
 33. The sealingcomposition of claim 28 wherein said organosilane coupling agent ispresent in an amount in the range of from about 0.1% to about 3% byweight thereof.
 34. The sealing composition of claim 28 wherein saidcationic surfactant is selected from the group consisting of ethoxylatednonyl phenol phosphate ester, C₁₂-C₂₂ alkyl phosphonates and mixtures ofone or more cationic surfactants and one or more non-ionic surfactants.35. The sealing composition of claim 28 wherein said cationic surfactantis a C₁₂-C₂₂ alkyl phosphonate.
 36. The sealing composition of claim 28wherein said cationic surfactant is present in an amount in the range offrom about 0.1% to about 10% by weight thereof.
 37. The sealingcomposition of claim 28 wherein said hollow microspheres are selectedfrom the group consisting of hollow mineral glass spheres, hollowsilica-alumina spheres, glass spheres and ceramic spheres.
 38. Thesealing composition of claim 28 wherein said hollow microspheres aremineral glass spheres.
 39. The sealing composition of claim 28 whereinsaid hollow microspheres are present in an amount in the range of fromabout 5% to about 50% by weight thereof.
 40. The sealing composition ofclaim 28 which further comprises a solvent or diluent selected from thegroup consisting of 2-butoxy ethanol, butyl acetate, furfuryl acetateand miktures thereof.
 41. The sealing composition of claim 40 whereinsaid solvent or diluent is furfuryl acetate.
 42. The sealing compositionof claim 40 wherein said solvent or diluent is present in an amount inthe range of from about 5% to about 60% by weight thereof.
 43. Thesealing composition of claim 28 which further comprises a dispersingagent selected from the group consisting ofnaphthalene-sulfonate-formaldehyde condensate,acetone-formaldehyde-sulfite condensate and glucano-delta-lactone. 44.The sealing composition of claim 43 wherein said dispersing agent isnaphthalene-sulfonate-formaldehyde condensate.
 45. The sealingcomposition of claim 43 wherein said dispersing agent is present in anamount in the range of from about 0.1% to about 10% by weight thereof.46. The sealing composition of claim 28 which further comprises alightweight filler selected from the group consisting of amorphoussilica, fumed silica, diatomaceous earth, and fly ash.
 47. The sealingcomposition of claim 46 wherein said lightweight filler is amorphoussilica.
 48. The sealing composition of claim 46 wherein said lightweightfiller is present in an amount in the range of from about 5% to about50% by weight thereof.
 49. The sealing composition of claim 28 whichfurther comprises sand.
 50. The sealing composition of claim 49 whereinsaid sand has a mesh size in the range of from about 70 mesh to about140 mesh.
 51. The sealing composition of claim 49 wherein said sand ispresent in an amount in the range of from about 5% to about 30% byweight thereof.
 52. The sealing composition of claim 28 which furthercomprises a delayed catalyst for causing said sealing composition toharden selected from the group consisting of encapsulated hydrochloricacid, encapsulated maleic acid, encapsulated salicylic acid andencapsulated sodium bisulfate.
 53. The sealing composition of claim 52wherein said delayed catalyst is encapsulated sodium bisulfate.
 54. Thesealing composition of claim 52 wherein said delayed catalyst is presentin an amount in the range of from about 0.1% to about 5% by weightthereof.